Methods and apparatuses for reference signal configuration

ABSTRACT

Embodiments of the present disclosure relate to methods and apparatuses for Reference Signal (RS) transmission. In example embodiments, a method implemented in a network device is provided. According to the method, the network device determines at least one set of CSI-RS resources for transmitting Tracking Reference Signal (TRS) to a terminal device. The network device further determines a first offset between a first slot to transmit a first signal for enabling transmission of the TRS and a second slot to transmit the TRS in the at least one set of CSI-RS resources. The first offset is different from a second offset between a third slot to transmit a second signal for enabling transmission of CSI-RS and a fourth slot to transmit the CSI-RS. The network device transmits a configuration indicating the at least one set of CSI-RS resources and the first offset to the terminal device.

TECHNICAL FIELD

Embodiments of the present disclosure generally relate to the field oftelecommunication, and in particular, to methods and apparatuses forreference signal configuration.

BACKGROUND

With the development of communication technologies, multiple types ofservices or traffic have been proposed, for example, enhanced mobilebroadband (eMBB) generally requiring high data rate, massive machinetype communication (mMTC) typically requiring long battery lifetime, andultra-reliable and low latency communication (URLLC). Meanwhile,multi-antenna schemes, such as beam management, reference signal (RS)transmission, and so on, are studied for new radio access (NR).

In NR, it has been agreed that Channel State Information-ReferenceSignal (CSI-RS) can be used for different purposes, such as, for ChannelState Information (CSI) acquisition, for beam management, for finetime-frequency tracking, for mobility, and so on. For example, CSI-RSfor time-frequency tracking is also referred to as “Tracking ReferenceSignal (TRS)”. CSI-RS can be divided into different types according toits behavior in time domain, such as periodic CSI-RS (P-CSI-RS),aperiodic CSI-RS (A-CSI-RS) and semi-persistent CSI-RS (SP-CSI-RS). Incurrent spec, only P-CSI-RS can be used for time-frequency tracking.That is, only periodic TRS can be supported at present.

It is desirable to enable aperiodic TRS for accelerating secondary cellactivation. However, the detailed solution for non-periodic TRS has notbeen provided yet.

SUMMARY

In general, example embodiments of the present disclosure providemethods and apparatuses for RS configuration.

In a first aspect, there is provided a method implemented in a networkdevice.

According to the method, the network device determines at least one setof CSI-RS resources for transmitting TRS to a terminal device. Thenetwork device further determines a first offset between a first slot totransmit a first signal for enabling transmission of the TRS and asecond slot to transmit the TRS in the at least one set of CSI-RSresources. The first offset is different from a second offset between athird slot to transmit a second signal for enabling transmission ofCSI-RS and a fourth slot to transmit the CSI-RS. The network devicetransmits a configuration indicating the at least one set of CSI-RSresources and the first offset to the terminal device.

In a second aspect, there is provided a method implemented in a terminaldevice. According to the method, the terminal device receives, from anetwork device, a configuration that indicates at least one set ofCSI-RS resources for receiving TRS from the network device and a firstoffset between a first slot to receive a first signal for enablingtransmission of the TRS and a second slot to receive the TRS in the atleast one set of CSI-RS resources. The first offset is different from asecond offset between a third slot to receive a second signal forenabling transmission of CSI-RS and a fourth slot to receive the CSI-RS.The terminal device determines, based on the configuration, the at leastone of CSI-RS resources and the first offset.

In a third aspect, there is provided a network device. The networkdevice comprises a processor and a memory coupled to the processor. Thememory stores instructions that when executed by the processor, causethe network device to perform actions. The actions include: determiningat least one set of CSI-RS resources for transmitting TRS to a terminaldevice; determining a first offset between a first slot to transmit afirst signal for enabling transmission of the TRS and a second slot totransmit the TRS in the at least one set of CSI-RS resources, the firstoffset being different from a second offset between a third slot totransmit a second signal for enabling transmission of CSI-RS and afourth slot to transmit the CSI-RS; and transmitting, to the terminaldevice, a configuration indicating the at least one set of CSI-RSresources and the first offset.

In a fourth aspect, there is provided a terminal device. The terminaldevice comprises a processor and a memory coupled to the processor. Thememory stores instructions that when executed by the processor, causethe terminal device to perform actions. The actions include: receiving,from a network device, a configuration that indicates at least one setof CSI-RS resources for receiving TRS from the network device and afirst offset between a first slot to receive a first signal for enablingtransmission of the TRS and a second slot to receive the TRS in the atleast one set of CSI-RS resources, the first offset being different froma second offset between a third slot to receive a second signal forenabling transmission of CSI-RS and a fourth slot to receive the CSI-RS;and determining, based on the configuration, the at least one set ofCSI-RS resources and the first offset.

In a fifth aspect, there is provided a computer readable medium havinginstructions stored thereon. The instructions, when executed on at leastone processor, cause the at least one processor to carry out the methodaccording to the first aspect of the present disclosure.

In a sixth aspect, there is provided a computer readable medium havinginstructions stored thereon. The instructions, when executed on at leastone processor, cause the at least one processor to carry out the methodaccording to the second aspect of the present disclosure.

In a seventh aspect, there is provided a computer program product thatis tangibly stored on a computer readable storage medium. The computerprogram product includes instructions which, when executed on at leastone processor, cause the at least one processor to carry out the methodaccording to the first aspect or the second aspect of the presentdisclosure.

Other features of the present disclosure will become easilycomprehensible through the following description.

BRIEF DESCRIPTION OF THE DRAWINGS

Through the more detailed description of some embodiments of the presentdisclosure in the accompanying drawings, the above and other objects,features and advantages of the present disclosure will become moreapparent, wherein:

FIG. 1 is a block diagram of a communication environment in whichembodiments of the present disclosure can be implemented;

FIG. 2 shows a process for TRS transmission according to someimplementations of the present disclosure;

FIG. 3 shows an example of TRS transmission according to someembodiments of the present disclosure;

FIG. 4 shows an example of multi-TRP CSI measurement in accordance withsome embodiments of the present disclosure;

FIG. 5 shows a flowchart of an example method for TRS configurationaccording to some embodiments of the present disclosure;

FIG. 6 shows a flowchart of an example method for TRS configurationaccording to some embodiments of the present disclosure; and

FIG. 7 is a simplified block diagram of a device that is suitable forimplementing embodiments of the present disclosure.

Throughout the drawings, the same or similar reference numeralsrepresent the same or similar element.

DETAILED DESCRIPTION

Principle of the present disclosure will now be described with referenceto some example embodiments. It is to be understood that theseembodiments are described only for the purpose of illustration and helpthose skilled in the art to understand and implement the presentdisclosure, without suggesting any limitations as to the scope of thedisclosure. The disclosure described herein can be implemented invarious manners other than the ones described below.

In the following description and claims, unless defined otherwise, alltechnical and scientific terms used herein have the same meaning ascommonly understood by one of ordinary skills in the art to which thisdisclosure belongs.

As used herein, the term “network device” or “base station” (BS) refersto a device which is capable of providing or hosting a cell or coveragewhere terminal devices can communicate. Examples of a network deviceinclude, but not limited to, a Node B (NodeB or NB), an Evolved NodeB(eNodeB or eNB), a next generation NodeB (gNB), a Transmission ReceptionPoint (TRP), a Remote Radio Unit (RRU), a radio head (RH), a remoteradio head (RRH), a low power node such as a femto node, a pico node,and the like. For the purpose of discussion, in the following, someembodiments will be described with reference to gNB as examples of thenetwork device.

As used herein, the term “terminal device” refers to any device havingwireless or wired communication capabilities. Examples of the terminaldevice include, but not limited to, user equipment (UE), personalcomputers, desktops, mobile phones, cellular phones, smart phones,personal digital assistants (PDAs), portable computers, image capturedevices such as digital cameras, gaming devices, music storage andplayback appliances, or Internet appliances enabling wireless or wiredInternet access and browsing and the like. For the purpose ofdiscussion, in the following, some embodiments will be described withreference to UE as examples of the terminal device.

As used herein, the singular forms “a”, “an” and “the” are intended toinclude the plural forms as well, unless the context clearly indicatesotherwise. The term “includes” and its variants are to be read as openterms that mean “includes, but is not limited to.” The term “based on”is to be read as “at least in part based on.” The term “one embodiment”and “an embodiment” are to be read as “at least one embodiment.” Theterm “another embodiment” is to be read as “at least one otherembodiment.” The terms “first,” “second,” and the like may refer todifferent or same objects. Other definitions, explicit and implicit, maybe included below.

In some examples, values, procedures, or apparatus are referred to as“best,” “lowest,” “highest,” “minimum,” “maximum,” or the like. It willbe appreciated that such descriptions are intended to indicate that aselection among many used functional alternatives can be made, and suchselections need not be better, smaller, higher, or otherwise preferableto other selections.

FIG. 1 shows an example communication network 100 in whichimplementations of the present disclosure can be implemented. Thenetwork 100 includes a network device 110 and a terminal device 120served by the network device 110. The network 100 can provide at leastone serving cell 102 to serve the terminal device 120. It is to beunderstood that the number of network devices, terminal devices and/orserving cells is only for the purpose of illustration without suggestingany limitations. The network 100 may include any suitable number ofnetwork devices, terminal devices and/or serving cells adapted forimplementing implementations of the present disclosure.

For example, in some scenarios, carrier aggregation (CA) can besupported in the network 100, in which two or more component carriers(CCs) are aggregated in order to support a broader bandwidth. In CA, thenetwork device 110 may provide a plurality of serving cells (forexample, one for each of the CCs) including one primary cell (PCell) andat least one secondary cell (SCell) to serve the terminal device 120.The terminal device 120 can establish Radio Resource Control (RRC)connection with the network device 110 in the PCell. The SCell canprovide additional radio resources once the RRC connection between thenetwork device 110 and the terminal device 120 is established and theSCell is activated via higher layer signaling.

In the communication network 100, the network device 110 can communicatedata and control information to the terminal device 120 and the terminaldevice 120 can also communication data and control information to thenetwork device 110. A link from the network device 110 to the terminaldevice 120 is referred to as a downlink (DL), while a link from theterminal device 120 to the network device 110 is referred to as anuplink (UL).

The communications in the network 100 may conform to any suitablestandards including, but not limited to, Global System for MobileCommunications (GSM), Long Term Evolution (LTE), LTE-Evolution,LTE-Advanced (LTE-A), Wideband Code Division Multiple Access (WCDMA),Code Division Multiple Access (CDMA), GSM EDGE Radio Access Network(GERAN), and the like. Furthermore, the communications may be performedaccording to any generation communication protocols either currentlyknown or to be developed in the future. Examples of the communicationprotocols include, but not limited to, the first generation (1G), thesecond generation (2G), 2.5G, 2.75G, the third generation (3G), thefourth generation (4G), 4.5G, the fifth generation (5G) communicationprotocols.

In addition to normal data communications, the network device 110 maysend a RS to the terminal device 120 in a downlink. Similarly, theterminal device 120 may transmit a RS to the network device 110 in anuplink. Generally speaking, a RS is a signal sequence (also referred toas “RS sequence”) that is known by both the network device 110 and theterminal devices 120. For example, a RS sequence may be generated andtransmitted by the network device 110 based on a certain rule and theterminal device 120 may deduce the RS sequence based on the same rule.Examples of the RS may include but are not limited to downlink or uplinkDemodulation Reference Signal (DMRS), CSI-RS, Sounding Reference Signal(SRS), Phase Tracking Reference Signal (PTRS) and so on. For the purposeof discussion without suggesting any limitations, in the followingdescription, some embodiments will be described with reference to CSI-RSas examples of the RS. Prior to transmission of CSI-RS, the networkdevice 110 may allocate corresponding resources (also referred to as“CSI-RS resources”) for the transmission. As used herein, a CSI-RSresource refers to one or more resource elements (REs) allocated forCSI-RS transmission in time, frequency, and/or code domains.

In NR, it has been agreed that CSI-RS can be used for differentpurposes, such as, for channel measurement (such as, CSI acquisition),for beam management, for fine time-frequency tracking, for mobility, andso on. CSI-RS can be divided into different types according to itsbehavior in time domain, such as periodic CSI-RS (P-CSI-RS), aperiodicCSI-RS (A-CSI-RS) and semi-persistent CSI-RS (SP-CSI-RS). As usedherein, “P-CSI-RS” refers to the CSI-RS which is transmittedperiodically in time domain. “SP-CSI-RS” is similar to P-CSI-RS exceptthat the transmission of SP-CSI-RS can be activated by a signal anddeactivated by another signal. “A-CSI-RS” refers to the CSI-RS whosetransmission can be triggered by the network device via triggersignaling (such as, Downlink Control Information (DCI)).

Different time offsets associated with A-CSI-RS have been designed andagreed in 3GPP specification works. For example, it has been agreed thatif UL assignment (for example, Physical Downlink Control Channel (PDCCH)carrying DCI) is transmitted in slot N, the A-CSI-RS will be transmittedin slot N+X. In some embodiments, the A-CSI-RS triggering offset X maybe fixed to zero or configurable on basis of per CSI-RS resource set.The offset X may be measured in slots.

As described above, CSI-RS for time-frequency tracking is also referredto as “TRS”. In current 3GPP specification works, only P-CSI-RS can beused for time-frequency tracking. That is, only periodic TRS can besupported at present. It is desirable to support aperiodic TRS foraccelerating SCell activation. However, the detailed solution fornon-periodic TRS has not been provided yet.

In order to solve the problems above and one or more of other potentialproblems, a solution for TRS configuration is provided in accordancewith example embodiments of the present disclosure. With the solution,the transmission of aperiodic TRS can be supported for assisting SCellactivation.

Principle and implementations of the present disclosure will bedescribed in detail below with reference to FIG. 2, which shows aprocess 200 for TRS transmission according to some implementations ofthe present disclosure. For the purpose of discussion, the process 200will be described with reference to FIG. 1. The process 200 may involvethe network device 110 and the terminal device 120 in FIG. 1.

As shown in FIG. 2, in some embodiments, the network device 110determines (210) a configuration for transmitting TRS to the terminaldevice 120.

In some embodiments, the configuration determined by the network device110 may indicate at least one set of CSI-RS resources for transmittingTRS to the terminal device 120. In the following, the “set of CSI-RSresources”, “CSI-RS resource set” and “resource set” can be usedinterchangeably. In some embodiments, one CSI-RS resource set mayinclude one or more CSI-RS resources.

In some embodiments, for different scenarios, the CSI-RS resources forTRS transmission may have different patterns. As used herein, the“pattern” of the CSI-RS resources may indicate a distribution of theCSI-RS resources in one or more slots in time domain. For example, insome embodiments, one CSI-RS resource set with two periodic CSI-RSresources in one slot can be determined for TRS transmission. Thispattern is also referred to as “one slot pattern” herein. In someembodiments, one CSI-RS resource set with four periodic CSI-RS resourcesin two consecutive slots can be determined for TRS transmission.Alternatively, in some embodiments, two CSI-RS resource sets each withtwo periodic CSI-RS resources in one slot can be determined for TRStransmission. Both of the above two patterns are also referred to as“two slot pattern” herein.

In some embodiments, the at least one CSI-RS resource set may beconfigured with higher layer parameter TRS-Info to indicate that the atleast one CSI-RS resource set can be used for TRS transmission. In casethat a CSI-RS resource set is configured with higher layer parameterTRS-Info, it can be assumed that the antenna port with the same portindex of the configured CSI-RS resources in the CSI-RS resource set issame.

In some embodiments, the configuration determined by the network device110 for TRS transmission may also indicate periodicity and/or a slotoffset for the TRS.

In some embodiments, the TRS to be transmitted from the network device110 to the terminal device 120 may be aperiodic TRS (A-TRS). That is,the transmission of the TRS can be triggered by the network device 110via trigger signaling, such as, PDCCH carrying DCI.

FIG. 3 shows an example of such embodiments. As shown in FIG. 3, thetrigger signaling is transmitted in slot N, while the TRS is transmittedin slot N+K. In some embodiments, the configuration determined by thenetwork device 110 for TRS transmission may indicate the slot offset(such as, K) between a first slot (such as, slot N) to transmit thetrigger signaling for enabling the transmission of the TRS and a secondslot (such as, slot N+K) to transmit the TRS in the at least one CSI-RSresource set.

In some embodiments, the slot offset for A-TRS used for time-frequencytracking may be different from the slot offset for ordinary A-CSI-RSused for other purposes. In some embodiments, A-TRS and A-CSI-RS may beassociated with different parameters. For example, Quasi-Co-Location(QCL) parameters configured for A-TRS may be different from thoseconfigured for ordinary A-CSI-RS. As such, the slot offsets for A-PTSand

A-CSI-RS may be different.

In some embodiments, a predefined set of candidate offsets S₁ may beconfigured for A-TRS. In this case, the network device 110 may selectthe slot offset for A-TRS from the predefined set S₁. In someembodiments, another set of candidate offsets S₂ may be configured forA-CSI-RS. In some embodiments, the set of candidate offsets S₁ for A-TRSmay at least in part differ from the set of candidate offsets S₂ forA-CSI-RS. For example, if a CSI-RS resource set is configured withhigher layer parameter TRS-Info, the slot offset associated with theCSI-RS resource set may be determined from the set of candidate offsetsS₁. If the CSI-RS resource set is not configured with higher layerparameter TRS-Info, the slot offset associated with the CSI-RS resourceset may be determined from the set of candidate offsets S₂. In someembodiments, the value of the slot offset for A-TRS cannot be 0.Alternatively, or in addition, in some embodiments, the slot offset forA-TRS may exceed a predetermined threshold, such as X slots or Y us.That is because if the TRS is trigged for other CC than the primary CC,the terminal device may need a Radio Frequency (RF) returning.Therefore, the slot offset needs to exceed a certain value.

In some embodiments, there may be a set of candidate slot offset valuesconfigured for aperiodic RS. For example, the slot offset may be theoffset between the transmission of triggering information (for example,PDCCH or DMRS of PDCCH) of aperiodic RS and the transmission of theaperiodic RS in terms of slot. In some embodiments, the aperiodic RS maybe at least one of CSI-RS, TRS, SRS, DMRS, PTRS, and positioning RS(PRS). In some embodiments, for different configurations of the RS (suchas, RS resource, RS resource set, CSI report setting and/or TransmissionConfiguration Indicator (TCI) state), at least one value in the set ofcandidate slot offset values may be different. In some embodiments, fordifferent configurations of the RS (such as, RS resource, RS resourceset, CSI report setting and/or Transmission Configuration Indicator(TCI) state), the number of values in the set of candidate slot offsetvalues may be different. In some embodiments, for differentconfigurations of the RS (such as, RS resource, RS resource set, CSIreport setting and/or Transmission Configuration Indicator (TCI) state),the minimum value in the set of candidate slot offset values may bedifferent. In some embodiments, the configuration of the RS may includeat least one of RS functionality, CSI report quantity, TRS-Info, valueof TCI state, QCL type, and QCL referred RS. In some embodiments, for afirst configuration of the RS, the set of candidate slot offset valuesmay be represented as S₁, (for example, S₁={S_(1_1), S_(1_2), S_(1_3), .. . S_(1_N)}, where N is the number of values in S₁) and for a secondconfiguration of the RS, the set of candidate slot offset values may berepresented as S₂, (for example, S₂ may be {S_(2_1), S_(2_2), S_(2_3), .. . S_(2_M)}, where M is the number of values in S₂). In someembodiments, the first configuration may indicate that the higher layerparameter TRS-Info is set to be TRUE or 1, which means, for example, theRS may be used for time-frequency tracking. The second configuration mayindicate that the higher layer parameter TRS-Info is set to be False or0, which means, for example, the RS may not be used for time-frequencytracking. In some embodiments, the first configuration may indicate thatthe QCL referred RS and/or QCL type for the transmission of RStriggering information (for example, PDCCH or DMRS of PDCCH) isdifferent from that for RS transmission. The second configuration mayindicate that the QCL referred RS and/or QCL type for the transmissionof RS triggering information (for example, PDCCH or DMRS of PDCCH) isthe same as that for the transmission of the RS. In some embodiments,the first configuration may indicate the cell, Bandwidth part (BWP),frequency range and/or CC for the transmission of RS triggeringinformation. The second configuration may indicate the cell, BWP,frequency range and/or CC for RS transmission. The first configurationmay be different from the second configuration. In some embodiments, ifthe first and second configurations are different, at least one value inS₁ may not be included in S₂. In some embodiments, if the first andsecond configurations are different, the number of values in S₁ may bedifferent from the number of values in S₂, that is N≠M. In someembodiments, if the first and second configurations are different, theminimum value in S₁ may be different from the minimum value in S₂. Insome embodiments, for the first configuration, there may be no value 0in S₁, or all of the values in S₁ may not be less than a predeterminedpositive value, such as X slots or Y us.

In some embodiments, the slot offset for A-TRS can be determined onbasis of per CSI-RS resource set. Specifically, in some embodiments, theslot offset may be determined based on the pattern of the at least oneCSI-RS resource set. In some embodiments, for one slot pattern, oneCSI-RS resource set with two periodic CSI-RS resources in one slot maybe configured for TRS transmission. In this case, the slot offset can bedetermined on basis of the one CSI-RS resource set. That is, the offsetindicates the number of slots between the slot containing the DCI thattriggers the transmission of the TRS and the slot in which TRS istransmitted in the one CSI-RS resource set.

In some embodiments, for two slot pattern, one CSI-RS resource set withfour periodic CSI-RS resources in two consecutive slots may bedetermined for TRS transmission. In this case, the slot offset for A-TRScan be determined on basis of the previous one of the two consecutiveslots. That is, the offset indicates the number of slots between theslot containing the DCI that triggers the transmission of the TRS andthe slot in which TRS is transmitted in the two periodic CSI-RSresources in the previous one of the two consecutive slots.

In some embodiments, for two slot pattern, two CSI-RS resource sets eachwith two periodic CSI-RS resources in one slot may be configured for TRStransmission. In this case, one DCI can trigger both of the two CSI-RSresource sets. The slot offset for A-TRS can be determined on basis ofat least one of the two CSI-RS resource sets. For example, assume thatthe slot offset determined for one of the two CSI-RS resource sets is mand the slot offset determined for the other of the two CSI-RS resourcesets is p. In some embodiments, p=m+1. In some other embodiments, p=m−1.In some embodiments, if two CSI-RS resource sets are triggered in asingle DCI or in a single slot, the two CSI-RS resource sets may beregarded as one TRS resource set. Alternatively, or in addition, in thiscase it can be assumed that the antenna port with the same port index ofthe configured CSI-RS resources in the two CSI-RS resource sets is same.In some embodiments, there may be one additional parameter or indicatorin the two CSI-RS resource sets to indicate whether the two CSI-RSresource sets can be used as one TRS resource set, or whether it can beassumed that the antenna port with the same port index of the configuredCSI-RS resources in the two CSI-RS resource sets is same or not. In someembodiments, the additional parameter or indicator may be represented as“TRS-single”. It is to be understood that other representation can alsobe used. In some embodiments, if the TRS-single is set to be apredetermined value or state A, the two CSI-RS resource sets may not beregarded as one TRS set or it cannot be assumed that the antenna portwith the same port index of the configured CSI-RS resources in the twoCSI-RS resource sets is same. If the TRS-single is set to anotherpredetermined value or state B, which is different from A, the twoCSI-RS resource sets may be regarded as one TRS set or it can be assumedthat the antenna port with the same port index of the configured CSI-RSresources in the two CSI-RS resource sets is same. In some embodiments,the additional parameter or indicator may be configured for each CSI-RSresource set or each of the CSI-RS resource sets triggered by the sameDCI or same slot. In some embodiments, the additional parameter orindicator may be configured for the two CSI-RS resource sets triggeredby the DCI.

In some embodiments, the TRS to be transmitted from the network device110 to the terminal device 120 may be semi-persistent TRS (SP-TRS). Thatis, once the transmission of the SP-TRS is activated by the networkdevice 110 via first signaling (such as, PDCCH or Media Access Control(MAC) Control Element (CE)), the SP-TRS can be transmitted periodicallylike periodic TRS (P-TRS). In some embodiments, the transmission of theSP-TRS can be deactivated by the network device 110 via second signaling(such as, PDCCH or MAC CE). In some embodiments, the transmission of theSP-TRS may be implicitly deactivated in case of at least one of thefollowing: the terminal device receives the RRC signaling; the terminaldevice reports the acknowledgement (ACK) for the RRC signaling for P-TRStransmission; the terminal device reports a valid Channel qualityindicator (CQI); or the terminal device successfully decode the PDCCH orsome other channel on the same BWP, cell, CC, frequency range, SCell,PCell and/or primary SCell.

In some embodiments, for SP-TRS, the periodicity and the slot offset canthe same as those configured for P-TRS, respectively. Specifically, theslot offset for SP-TRS can be on a basis of per CSI-RS resource.

In some embodiments, the slot offset (such as, Q) for SP-TRS mayindicate the number of slots between the slot (such as, slot M)containing the first signaling (such as, PDCCH or MAC CE) that activatesthe transmission of the SP-TRS and the slot (such as, slot M+Q) fromwhich the effective transmission of SP-TRS begins.

In some embodiments, the slot offset Q for SP-TRS can be fixed to be apredetermined value. In some embodiments, the slot offset Q for SP-TRSmay be fixed to be an absolute time interval, for example, Kmicroseconds. In some embodiments, the actual value of the slot offset Qmay be calculated based on the time interval K and the value ofsubcarrier spacing (SCS) S_(c) for the SP-TRS. For example, the value ofthe slot offset Q can be determined by rounding up or down the number ofslots within the time interval K. For example, the value of K cannot be0.

In some embodiments, the slot offset Q for SP-TRS can be determinedbased on the value of subcarrier spacing (SCS) for the SP-TRS. Forexample, for a given value of SCS, the slot offset K for SP-TRS can befixed.

In some embodiments, the slot offset Q for SP-TRS can be configurableand may be determined from a set of candidate offsets predefined forSP-TRS. In some embodiments, if the configuration (such as, QCL type,QCL referred RS, the cell, the BWP, the frequency range and/or the CC)for the transmission of the first signaling (such as, PDCCH or MAC CE)is the same that for SP-TRS transmission, the value of the slot offset Qfor SP-TRS may be q₁. If the configuration (such as, QCL type, QCLreferred RS, the cell, the BWP, the frequency range and/or the CC) forthe transmission of the first signaling (such as, PDCCH or MAC CE) isdifferent from that for SP-TRS transmission, the value of the slotoffset Q for SP-TRS may be q₂, where q₁≠q₂. For example, the set ofcandidate offsets predefined for SP-TRS may not include the value ‘0’.

In some embodiments, there may be respective P-TRS configuration for TRStransmission in SCell, Pcell or PSCell. For example, a TRS configurationmay indicate at least one of the following: the frequency resourcewithin one slot, the time resource within one slot, the symbol index,the periodicity, the slot offset, and so on. In some embodiments, thefrequency resource within one slot, the time resource within one slot,the symbol index, the periodicity and/or the slot offset configured foractivated SP-TRS may be the same as that configured for P-TRS. In someembodiments, there may be additional configurations on the periodicityand/or slot offset for SP-TRS. For example, in addition to sharing someconfigurations with P-TRS, it may only be necessary to additionallyconfigure the periodicity and/or slot offset for SP-TRS. In someembodiments, the periodicity for SP-TRS transmission may be the same asthat configured for P-TRS. In addition, the actual index of the slot fortransmitting SP-TRS may be determined based on the index of the slotcontaining the first signaling (such as, PDCCH or MAC CE) for SP-TRSactivation and the slot offset Q for SP-TRS.

In some cases, the activated SP-TRS may have a different SCS from thetrigger signaling (such as, PDCCH or MAC CE). For example, the SCS forthe activated SP-TRS may be SCS1, and the SCS for the activating PDCCHor MAC CE is SCS2, where SCS1≠SCS2. In some embodiments, in this case,the slot offset Q for SP-TRS may be determined based on the SCS for theactivated SP-TRS, that is, SCS1.

Returning to FIG. 2, the network device 110 transmits (220) theconfiguration for TRS transmission to the terminal device 120. Forexample, the configuration for TRS transmission may indicate the atleast one CSI-RS resource set configured with the parameter TRS-Info,the slot offset between the first slot to transmit the trigger and/oractivation signaling for enabling the transmission of the TRS and thesecond slot to transmit the TRS in the at least one CSI-RS resource set,and so on.

As shown in FIG. 2, in response to receiving the configuration for TRStransmission from the network device 110, the terminal device 120 maydetermine (230) the at least one CSI-RS resource set and the slot offsetfor TRS transmission based on the configuration.

The network device 110 then transmits (240) the trigger signaling andthe TRS to the terminal device 120 at least based on the configuration.Specifically, the network device 110 may transmit the trigger and/oractivation signaling in the first slot and transmits the TRS with the atleast one CSI-RS resource set in the second slot to the terminal device120. The terminal device 120 may receive the trigger and/or activationsignaling and the TRS from the network device 110 at least based on thereceived configuration. Specifically, the terminal device 120 mayreceive the trigger and/or activation signaling in the first slot andtransmits the TRS with the at least one CSI-RS resource set in thesecond slot from the network device 110.

In NR, multi-TRP transmission can be supported. In order to performmulti-TRP CSI measurement, a solution for multi-TRP CSI measurement isprovided in accordance with example embodiments of the presentdisclosure.

FIG. 4 shows an example of multi-TRP CSI measurement in accordance withsome embodiments of the present disclosure. As shown in FIG. 4, aterminal device 410 can be served by two TRPs 420-1 and 420-2. It is tobe understood that the number of terminal devices and/or TRPs is onlyfor the purpose of illustration without suggesting any limitations.

In some embodiments, the terminal device 410 may support simultaneousreception from different TRPs. For example, as shown in FIG. 4, theterminal device 410 may support two spatial Rx beams 430-1 and 430-2. Insome embodiments, a pair of CSI-RS resources A and B can be configuredfor CSI-RS transmission from the TRPs 420-1 and 420-2. As shown in FIG.4, the terminal device 410 can receive, via the Rx beam 430-1 and fromthe TRP 420-1, CSI-RS transmitted in the CSI-RS resource A. Meanwhile,the terminal device 410 can receive, via the Rx beam 430-2 and from theTRP 420-1, CSI-RS transmitted in the CSI-RS resource B. In addition, theterminal device 410 can detect, via the Rx beam 430-1 and in the CSI-RSresource A, interference from the TRP 420-2. Meanwhile, the terminaldevice 410 can detect, via the Rx beam 430-2 and in the CSI-RS resourceB, interference from the TRP 420-1. That is, for the Rx beam 430-1, theCSI-RS resource A can be used for channel measurement and the CSI-RSresource B can be used for interference measurement. In someembodiments, for the Rx beam 430-1, Quasi-Co-Location (QCL) parametersand/or receiving beam of the CSI-RS resource B for interferencemeasurement may follow those of the CSI-RS resource A for channelmeasurement. Similarly, for the Rx beam 430-2, the CSI-RS resource B canbe used for channel measurement and the CSI-RS resource A can be usedfor interference measurement. In some embodiments, for the Rx beam430-2, the QCL parameters and/or receiving beam of the CSI-RS resource Afor interference measurement may follow those of the CSI-RS resource Bfor channel measurement. In this way, multi-TRP CSI measurement can beimplemented.

In some embodiments, a pair of CSI-RS resources (such as, the CSI-RSresource A with QCL parameter QCL-1 and the CSI-RS resource B with QCLparameter QCL-2) can be configured for the terminal device, and a pairof measurements may be performed by the terminal device. For example,the terminal device may measure the channel on the CSI-RS resource A andmeasure the interference on the CSI-RS resource B with QCL-1. Likewise,the terminal device may measure the channel on the CSI-RS resource B andmeasure the interference on the CSI-RS resource A with QCL-2. In someembodiments, there may be an additional parameter and/or indicator toconfigure the terminal device for the pair of measurements. In someembodiments, the terminal device may perform the pair of measurements ifconfigured with group-based reporting.

FIG. 5 shows a flowchart of an example method 500 in accordance withsome embodiments of the present disclosure. The method 500 can beimplemented at the network device 110 as shown in FIG. 1. For thepurpose of discussion, the method 500 will be described from theperspective of the network device 110 with reference to FIG. 1.

At block 510, the network device 110 determines at least one set ofChannel State Information-Reference Signal (CSI-RS) resources fortransmitting Tracking Reference Signal (TRS) to the terminal device 120.

At block 520, the network device 110 determines a first offset between afirst slot to transmit a first signal for enabling transmission of theTRS and a second slot to transmit the TRS in the at least one set ofCSI-RS resources.

At block 530, the network device 110 transmits, to the terminal device120, a configuration indicating the at least one set of CSI-RS resourcesand the first offset.

In some embodiments, the first offset is different from a second offsetbetween a third slot to transmit a second signal for enablingtransmission of CSI-RS and a fourth slot to transmit the CSI-RS. Forexample, the TRS and the CSI-RS may be associated with differentQuasi-Co-Location (QCL) parameters.

In some embodiments, the network device 110 may determine the at leastone set of CSI-RS resources by determining a distribution of the atleast one set of CSI-RS resources in one or more slots. The networkdevice 110 may determine the first offset based on the distribution.

In some embodiments, the distribution may indicate that the at least oneset of CSI-RS resources includes a first resource set with two periodicCSI-RS resources in one slot. The network device 110 may determine thefirst offset based on the first resource set.

In some embodiments, the distribution may indicate that the at least oneset of CSI-RS resources includes a second resource set with fourperiodic CSI-RS resources in two consecutive slots. The network device110 may determine the first offset based on at least one of the twoconsecutive slots.

In some embodiments, the distribution may indicate that the at least oneset of CSI-RS resources includes two resource sets each with twoperiodic CSI-RS resources in one slot. The network device 110 may obtaina first set of candidate offsets predefined for the TRS, and determinethe first offset from the first set of candidate offsets. In someembodiments, the first set of candidate offsets may be at least in partdifferent from a second set of candidate offsets predefined for theCSI-RS and the second offset may be determined from the second set ofcandidate offsets.

In some embodiments, the TRS is aperiodic.

In some embodiments, the TRS is semi-persistent. The network device 110may obtain a third offset preconfigured for periodic TRS, and determinethe first offset based on the third offset.

In some embodiments, the TRS may be associated with a first subcarrierspacing (SCS) and the first signal may be associated with a second SCSthat is different from the first SCS. The network device 110 maydetermine the first offset at least based on the first SCS.

In some embodiments, the network device 110 may transmit, at least basedon the configuration, the first signal and the TRS to the terminaldevice.

FIG. 6 shows a flowchart of an example method 600 in accordance withsome embodiments of the present disclosure. The method 600 can beimplemented at the terminal device 120 as shown in FIG. 1. For thepurpose of discussion, the method 500 will be described from theperspective of the terminal device 120 with reference to FIG. 1.

At block 610, the terminal device 120 receives, from the network device110, a configuration for TRS transmission. The configuration mayindicate at least one set of CSI-RS resources for receiving TRS from thenetwork device 110 and a first offset between a first slot to receive afirst signal for enabling transmission of the TRS and a second slot toreceive the TRS in the at least one set of CSI-RS resources.

At block 620, the terminal device 120 determines, based on theconfiguration, the at least one set of CSI-RS resources and the firstoffset.

In some embodiments, the first offset is different from a second offsetbetween a third slot to transmit a second signal for enablingtransmission of CSI-RS and a fourth slot to transmit the CSI-RS. Forexample, the TRS and the CSI-RS may be associated with differentQuasi-Co-Location (QCL) parameters.

In some embodiments, the TRS is aperiodic.

In some embodiments, the TRS is semi-persistent.

In some embodiments, the TRS may be associated with a first subcarrierspacing (SCS) and the first signal may be associated with a second SCSthat is different from the first SCS. The terminal device 120 maydetermine the first offset at least based on the first SCS.

In some embodiments, the terminal device 120 may receive, at least basedon the configuration, the first signal and the TRS from the networkdevice 110.

FIG. 7 is a simplified block diagram of a device 700 that is suitablefor implementing embodiments of the present disclosure. The device 700can be considered as a further example implementation of the networkdevice 110 as shown in FIG. 1. Accordingly, the device 700 can beimplemented at or as at least a part of the network device 110.

As shown, the device 700 includes a processor 710, a memory 720 coupledto the processor 710, a suitable transmitter (TX) and receiver (RX) 740coupled to the processor 710, and a communication interface coupled tothe TX/RX 740. The memory 710 stores at least a part of a program 730.The TX/RX 740 is for bidirectional communications. The TX/RX 740 has atleast one antenna to facilitate communication, though in practice anAccess Node mentioned in this application may have several ones. Thecommunication interface may represent any interface that is necessaryfor communication with other network elements, such as X2 interface forbidirectional communications between eNBs, S1 interface forcommunication between a Mobility Management Entity (MME)/Serving Gateway(S-GW) and the eNB, Un interface for communication between the eNB and arelay node (RN), or Uu interface for communication between the eNB and aterminal device.

The program 730 is assumed to include program instructions that, whenexecuted by the associated processor 710, enable the device 700 tooperate in accordance with the embodiments of the present disclosure, asdiscussed herein with reference to FIGS. 1 to 8. The embodiments hereinmay be implemented by computer software executable by the processor 610of the device 700, or by hardware, or by a combination of software andhardware. The processor 610 may be configured to implement variousembodiments of the present disclosure. Furthermore, a combination of theprocessor 610 and memory 610 may form processing means 750 adapted toimplement various embodiments of the present disclosure.

The memory 610 may be of any type suitable to the local technicalnetwork and may be implemented using any suitable data storagetechnology, such as a non-transitory computer readable storage medium,semiconductor based memory devices, magnetic memory devices and systems,optical memory devices and systems, fixed memory and removable memory,as non-limiting examples. While only one memory 610 is shown in thedevice 700, there may be several physically distinct memory modules inthe device 700. The processor 610 may be of any type suitable to thelocal technical network, and may include one or more of general purposecomputers, special purpose computers, microprocessors, digital signalprocessors (DSPs) and processors based on multicore processorarchitecture, as non-limiting examples. The device 700 may have multipleprocessors, such as an application specific integrated circuit chip thatis slaved in time to a clock which synchronizes the main processor.

Generally, various embodiments of the present disclosure may beimplemented in hardware or special purpose circuits, software, logic orany combination thereof. Some aspects may be implemented in hardware,while other aspects may be implemented in firmware or software which maybe executed by a controller, microprocessor or other computing device.While various aspects of embodiments of the present disclosure areillustrated and described as block diagrams, flowcharts, or using someother pictorial representation, it will be appreciated that the blocks,apparatus, systems, techniques or methods described herein may beimplemented in, as non-limiting examples, hardware, software, firmware,special purpose circuits or logic, general purpose hardware orcontroller or other computing devices, or some combination thereof.

The present disclosure also provides at least one computer programproduct tangibly stored on a non-transitory computer readable storagemedium. The computer program product includes computer-executableinstructions, such as those included in program modules, being executedin a device on a target real or virtual processor, to carry out theprocess or method as described above with reference to any of FIGS. 1 to7B. Generally, program modules include routines, programs, libraries,objects, classes, components, data structures, or the like that performparticular tasks or implement particular abstract data types. Thefunctionality of the program modules may be combined or split betweenprogram modules as desired in various embodiments. Machine-executableinstructions for program modules may be executed within a local ordistributed device. In a distributed device, program modules may belocated in both local and remote storage media.

Program code for carrying out methods of the present disclosure may bewritten in any combination of one or more programming languages. Theseprogram codes may be provided to a processor or controller of a generalpurpose computer, special purpose computer, or other programmable dataprocessing apparatus, such that the program codes, when executed by theprocessor or controller, cause the functions/operations specified in theflowcharts and/or block diagrams to be implemented. The program code mayexecute entirely on a machine, partly on the machine, as a stand-alonesoftware package, partly on the machine and partly on a remote machineor entirely on the remote machine or server.

The above program code may be embodied on a machine readable medium,which may be any tangible medium that may contain, or store a programfor use by or in connection with an instruction execution system,apparatus, or device. The machine readable medium may be a machinereadable signal medium or a machine readable storage medium. A machinereadable medium may include but not limited to an electronic, magnetic,optical, electromagnetic, infrared, or semiconductor system, apparatus,or device, or any suitable combination of the foregoing. More specificexamples of the machine readable storage medium would include anelectrical connection having one or more wires, a portable computerdiskette, a hard disk, a random access memory (RAM), a read-only memory(ROM), an erasable programmable read-only memory (EPROM or Flashmemory), an optical fiber, a portable compact disc read-only memory(CD-ROM), an optical storage device, a magnetic storage device, or anysuitable combination of the foregoing.

Further, while operations are depicted in a particular order, thisshould not be understood as requiring that such operations be performedin the particular order shown or in sequential order, or that allillustrated operations be performed, to achieve desirable results. Incertain circumstances, multitasking and parallel processing may beadvantageous. Likewise, while several specific implementation detailsare contained in the above discussions, these should not be construed aslimitations on the scope of the present disclosure, but rather asdescriptions of features that may be specific to particular embodiments.Certain features that are described in the context of separateembodiments may also be implemented in combination in a singleembodiment. Conversely, various features that are described in thecontext of a single embodiment may also be implemented in multipleembodiments separately or in any suitable sub-combination.

Although the present disclosure has been described in language specificto structural features and/or methodological acts, it is to beunderstood that the present disclosure defined in the appended claims isnot necessarily limited to the specific features or acts describedabove. Rather, the specific features and acts described above aredisclosed as example forms of implementing the claims.

What is claimed is:
 1. A method performed by a base station, the methodcomprising: transmitting, to a terminal device, first resourceconfiguration for transmission of a Channel State Information ReferenceSignal (CSI-RS) for tracking, wherein the first resource configurationcomprises: a parameter trs-Info set as true; and a first parameterindicating a first offset between a first slot containing a first signalthat triggers the transmission of the CSI-RS for tracking and a secondslot in which the CSI-RS for tracking is transmitted, wherein the firstoffset is independent from a second offset indicated by a secondparameter comprised in a second resource configuration for transmissionof a CSI-RS without the parameter trs-Info set as true, and wherein thesecond offset is between a third slot containing a second signal thattriggers the transmission of the CSI-RS and a fourth slot in which theCSI-RS is transmitted; and transmitting the CSI-RS for tracking, to theterminal device in the second slot.
 2. The method of claim 1, whereinthe CSI-RS for tracking and the CSI-RS are associated with differentQuasi-Co-Location (QCL) parameters.
 3. The method of claim 1, furthercomprising: determining the first resource configuration, whereindetermining the first resource configuration comprises: determining adistribution of at least one set of resources for the CSI-RS fortracking in one or more slots; and determining the first offset, whereindetermining the first offset comprises:  determining the first offsetusing the distribution.
 4. The method of claim 3, wherein thedistribution indicates that the at least one set of the resources forthe CSI-RS for tracking includes a first resource set with two periodicresources for the CSI-RS for tracking in one slot, and the determiningthe first offset comprises: determining the first offset using the firstresource set.
 5. The method of claim 3, wherein the distributionindicates that the at least one set of resources for the CSI-RS fortracking includes a second resource set with four periodic resources forthe CSI-RS for tracking in two consecutive slots, and the determiningthe first offset comprises: determining the first offset using at leastone of the two consecutive slots.
 6. The method of claim 3, wherein thedistribution indicates that the at least one set of resources for theCSI-RS for tracking includes two resource sets each with two periodicresources for the CSI-RS for tracking in one slot, and the determiningthe first offset comprises: determining the first offset using at leastone of the two resource sets.
 7. The method of claim 1, furthercomprising: determining the first offset, wherein determining the firstoffset comprises: obtaining a first set of candidate offsets predefinedfor the CSI-RS for tracking; and determining the first offset from thefirst set of candidate offsets, the first set of candidate offsets beingat least in part different from a second set of candidate offsets, thesecond offset being determined from the second set of candidate offsets.8. The method of claim 1, wherein the CSI-RS for tracking is aperiodic.9. The method of claim 1, wherein the first signal is transmitted in aDownlink Control Information (DCI) format.
 10. The method of claim 1,wherein the CSI-RS for tracking is associated with a first subcarrierspacing (SCS) and the first signal is associated with a second SCS thatis different from the first SCS, and wherein the method furthercomprises: determining the first offset, wherein determining the firstoffset comprises: determining the first offset at least using the firstSCS.
 11. The method of claim 1, further comprising: transmitting, atleast using the first resource configuration, the first signal and theCSI-RS for tracking to the terminal device.
 12. A method performed by aterminal device, the method comprising: receiving, from a base station,first resource configuration for transmission of a Channel StateInformation Reference Signal (CSI-RS) for tracking, wherein the firstresource configuration comprises: a parameter trs-Info set as true; anda first parameter indicating a first offset between a first slotcontaining a first signal that triggers the transmission of the CSI-RSfor tracking and a second slot in which the CSI-RS for tracking isreceived, wherein the first offset is independent from a second offsetindicated by a second parameter comprised in a second resourceconfiguration for transmission of a CSI-RS without the parametertrs-Info set as true, wherein the second offset is between a third slotcontaining a second signal that triggers the transmission of the CSI-RSand a fourth slot in which the CSI-RS is received; and receiving theCSI-RS for tracking from the base station in the second slot.
 13. Themethod of claim 12, wherein the CSI-RS for tracking and the CSI-RS areassociated with different Quasi-Co-Location (QCL) parameters.
 14. Themethod of claim 12, wherein the CSI-RS for tracking is aperiodic. 15.The method of claim 12, wherein the first signal is received in aDownlink Control Information (DCI) format.
 16. The method of claim 12,wherein the CSI-RS for tracking is associated with a first subcarrierspacing (SCS) and the first signal is associated with a second SCS thatis different from the first SCS, and wherein the first offset isdetermined at least using the first SCS.
 17. The method of claim 12,further comprising: receiving, at least using the first resourceconfiguration, the first signal and the CSI-RS for tracking from thebase station.
 18. A base station comprising: a transmitter configuredto: transmit, to a terminal device, first resource configuration fortransmission of a Channel State Information Reference Signal (CSI-RS)for tracking, wherein the first resource configuration comprises: aparameter trs-Info set as true; and a first parameter indicating a firstoffset between a first slot containing a first signal that triggers thetransmission of the CSI-RS for tracking and a second slot in which theCSI-RS for tracking is transmitted, wherein the first offset isindependent from a second offset indicated by a second parametercomprised in a second resource configuration for transmission of aCSI-RS without the parameter trs-Info set as true, and wherein thesecond offset is between a third slot containing a second signal thattriggers the transmission of the CSI-RS and a fourth slot in which theCSI-RS is transmitted; and transmit the CSI-RS for tracking to theterminal device in the second slot.